This invention is directed to apparatuses such as spinners, spinning wrenches, spinning tongs, and iron or hydraulic roughnecks (“spinners”) used for rotating drilling tubulars during oil and gas wellbore drilling operations.
Drilling tubulars such as drill pipe, tubing, and casing (“tubulars”) are assembled by threading one section of tubular to the next. A spinner provides the clamping and rotational force needed to spin in or spin out the threaded connection. The spinner includes arms with roller assemblies that grip or clamp onto the tubular. When in the clamping position, the tubular is contacted by a set of roller assemblies. Enough clamping force must be exerted perpendicular to the tubular to counteract the rotational force.
Using small diameter rollers for spinning small (outside) diameter tubulars such as 2⅞″ or less presents a problem in achieving sufficient gripping coefficient on the tubular. Therefore, larger (outside) diameter rollers—with their greater contact area and better geometry for transferring clamp force perpendicular to the torque force vector—are preferred. However, the larger diameter rollers can interfere with one another as they engage a much smaller diameter pipe. Because of the interference problem, some prior art spinners use multi-diameter rollers in which one roller provides the large contact surface and the opposing roller provides a recess to prevent interference.
EP 2 118 433 B1 discloses a set of solid body multi-diameter rollers in which one roller includes a projection and an opposing roller includes a recess for receiving at least part of the projection. The roller has no central shaft but is instead connected to the drive shaft of the spinner motor by way of an upper spindle. When one roller wears, the entire roller assembly must be replaced.
A need exists to spin small diameter pipe with large diameter rollers yet avoid the interference problem and complete roller replacement problem.